Isn't food poisoning non-fatal a vast majority of the time? Or were you using a broad definition of "okay?"

Yeah; obviously missing a day or two to just getting ill is a significant cost worth avoiding, but if you expect to live a long while the chance of death typically ends up being more important in terms of total cost (because it's worse than it is rarer, I believe).

I am far more lax than most people I know also--when I was growing up there were leftovers, but we couldn't afford to waste them unless they were really not good; I was still broke in college and would not turn my nose up at things other people were wary of. I have never been completely stupid about it, but I am not terribly afraid of food poisoning either, mostly because it barely registers on the list of risky activities I should worry about. (For comparison, I am convinced that my lack of driving skill would seriously injure myself or others, and so I don't drive, which apparently makes me weird.)

I have had food poisoning a handful of times--but mostly under conditions that even conscientiously hygienic people would consider fine... and once from dubious food while traveling, because really if you do not eat the street food you are wasting your airfare.

(gwillen, I swear I am not deliberately following you around!)

Can you try to summarize your rules of thumb on consumption of leftovers, and describe to what extent you think they've got a rational basis?

The primary things that come to mind are "if you notice anything off, dispose of it" and "store things in sealed containers with dates on post-it notes or written with dry erase markers," but most of the stuff I pay attention to these days are food prep rules (since I very rarely have leftovers, and most of the things I consume take a long time to go bad).

I think rating eating a dubious leftover as 10 micromorts comes from not taking numbers seriously. If you really think it's in that order of magnitude I would like to see the reasoning behind it.

The base rate of death due to food-borne illness in the US is 10 micromorts a year; there's a conversion from 'per year' numbers to 'per act' numbers, the issue of how much comes from food starting off bad and how much comes from food going bad, and the issue of how good you are at detecting a pathogen risk by smell/sight, and I fudged all three as coming out to 1 when combined. (You could also add in the risk of days lost to sickness in terms of micromorts, instead of separate units, but that would probably be unnecessarily confusing.)

The real point, though, was to demonstrate how you can agree on facts but disagree on values; even if we both put the same probability on the risk of death, one of us is moved by it and the other isn't. (As well, I have a specialized vocabulary specifically targeted at dealing with these tiny risks of death that he doesn't use as much.) That's what 'overhygienic' means to me: "look at how far they're willing to go to avoid death!"

How large is your sample size?

I've met probably ~100 LWers in person, but I notice that I was falling prey to confirmation / availability bias when writing the grandparent post. When I met up with Fluttershy for lunch in a restaurant, he took out the bottle of hand sanitizer he kept in his backpack, and that counted more heavily in my memory than the Seattle LW game night / group meal hosted at jsalvatier's place, where if I recall correctly people washed their hands in the sink if they wanted to, rather than there being some sort of explicit cleanliness norm, despite there being two LWers at the first event and ~twelve at the second. I can't recall a time when I thought a LWer was behaving in an obviously unclean manner, though, but that's rare enough anyway among people I'm around that I don't know how much evidence that is. (Thinking of the group I'm close to with the least overall healthiness, as evidenced by the prevalence of drinking, smoking, and (I'm pretty sure) promiscuity, even they throw out unrefrigerated leftovers with meat in it because of the influence of one of the members with a food service job (and thus the associated food safety training).)